Anyone over 30 will be able to get a second COVID-19 vaccine booster from Monday, although it is actively recommended only for people older than 50, states new ATAGI advice.

The group met on Wednesday to discuss broadening access to the so-called winter dose in the wake of Australia’s surging hospitalisations, driven by the highly infectious Omicron subvariants BA.4 and BA.5.

In a statement on Thursday, ATAGI also recommended the interval between booster doses should be reduced from four to three months, with the gap between COVID-19 infection and a booster remaining at three months.

Minister for Health Mark Butler said on Thursday that the broadening of criteria for the fourth vaccine dose meant an additional 7.4 million Australians would be eligible from Monday, 11 July.

The reach for a second booster dose had been expanded from the original target groups, which included the elderly, residents of aged care institutions, Indigenous people and the immunocompromised.

ATAGI said the winter dose was anticipated to boost immune response. However, the experts noted that as the new subvariants were deft at escaping the immune response to current vaccines, it was important to also boost the use of masks and antiviral treatments.

While the evidence was “less certain” for people aged 30-49, ATAGI said it recognised that some in the age group wanted to reduce their risk of infection.

“While rates of hospitalisation, severe disease and death from COVID-19 are low in this age group, other factors — such as time off work and the risk of long COVID — may influence an individual’s personal decision,” the group noted.

However, it ruled out expanding access to healthy adults under 30, indicating that it was still unclear whether the benefits of the extra dose outweighed the risk, citing the rare risk of myocarditis in young men that had been linked to mRNA vaccines.